The goal of the Genetics of Non-Insulin Dependent Diabetes Mellitus (NIDDM) (GENNID) study is to collect a renewable source of genetic material for linkage an similar studies of NIDDM, bases upon pedigrees ascertained from an affected sibling pair. During the current period (12/1/98 - 12/1/99) wee will recruit 30 extended pedigrees, including at least two affected sibs, an unaffected spouse control, and unaffected sibs and parents when available. Clinical and family histories will be recorded in a permanent database, along wit pertinent laboratory studies including measures of pancreatic islet b-cell function, insulin action, renal function, and lipid metabolism. Permanent cell lines will be established for an unlimited source of DNA. In addition, 30 families will be recruited with only affected sib pairs studied. This resource will provide the necessary materials for future investigators to pursue the genotypic determinants of diabetic phenotypes.